Preamplifier with bass and treble correction. The boost/cut of the left or right channel is 14dB. The slope of the subfilter is 24dB/oct. and the frequency of the subfilter is 120 Hz.
The upper potentiometer (2x47kOhm) of the left and right input is for adjusting low frequencies. The lower potentiometer (2x47kOhm) of the left and right input is for adjusting higher frequencies.
The middle potentiometer (2x5kOhm) of the right and left channels changes the volume.
The last potentiometer is the balance correction between the left and right channels.
Red line is Sound IN, blue and green is Sound OUT and orange is SUB OUT.
